Kinetic energy

Kinetic energy is the energy an object has because of its motion.

  • Planets, cars, people and atoms all have kinetic energy due to their motion.
  • When a force is applied to an object, its kinetic energy can change.
  • When one object strikes another, the force of the impact can transfer kinetic energy.
  • Kinetic energy is the energy of motion, while potential energy is the energy of position or state.
  • Most interactions between objects involve forces and can transfer energy.
  • Energy is the capacity to do work. It can exist in different forms such as kinetic, potential, thermal, and electromagnetic.
  • Energy cannot be created or destroyed; it can only be converted from one form to another
  • Force is a term used to describe the interaction between objects that causes a change in motion or shape.
  • Galaxies, human beings and electrons can all apply forces to the things around them.
  • Work is defined as the product of the force applied on an object and the distance it moves in the direction of the force.
  • Objects at absolute zero do not have any thermal energy to transfer, but they can still interact and exchange other forms of energy.
At an atomic scale
  • Electrical energy passes through a circuit as electrons flow, transferring their kinetic energy to other electrons in the circuit.
  • Heat is produced as photons strike an object, transferring their energy to electrons within the atoms or molecules of its surface.
At a human scale
  • The human senses of sight, hearing, and touch are tuned to respond to different forms of energy when a force is applied to them.
  • When a person hears a sound or sees something, that is evidence of energy having been transferred to their senses.
Here is an example
  • A person pushes a heavy boulder up a hill.
  • Each time they push they apply force to make the boulder move.
  • They feel exhausted by the time they reach the top because of the work involved in overcoming the force of gravity and friction.
  • But the energy is not lost, instead, it is transferred to the boulder as kinetic energy.
  • As soon as the boulder is released and starts to roll back down the hills, the kinetic energy it has gained is transferred to other boulders it crashes into.
  • If the boulder is too heavy to move, no work is done on the boulder. However, the person’s muscles still expend energy, which is released into the environment as heat.